Retorts for the pyrolysis of kerogen or other organic material found in carbonaceous materials such as oil shale, tar sands, coal and lignite, as presently designed, generally heat the carbonaceous materials to one temperature at which pyrolysis occurs, and the resulting liquid and/or gaseous products formed are then collected for processing. Alternative designs provide for heating the carbonaceous materials to different temperatures within the retort, but do not allow for the segregating of the products formed by pyrolysis at the varying temperatures. Therefore, in these retorts all fractions of hydrocarbons produced are allowed to mix with one another necessitating a costly fractionation procedure downstream. Furthermore, the temperatures in the different heating zones are not readily controllable, resulting in inefficient pyrolysis at the retort zone. The present invention is an apparatus and method for the selective retorting of hydrocarbon materials, which promotes efficient pyrolysis at varying temperatures and provides a means for separately withdrawing the liquid and/or gaseous products formed by pyrolysis so that fractionation downstream is simplified.
An example of a use to which the present invention could be put concerns the Devonian oil shales of the Eastern United States. Included within this class of shales are the New Albany shales of Indiana which in tests were seen to produce light gravity oil vapors when heated to approximately 350 degrees Fahrenheit, medium gravity oils at approximately 400 degrees Farenheit, a heavy gravity oil at approximately 550 degrees Fahrenheit, with an extremely heavy oil produced at 740 degrees Fahrenheit. Not only does this oil shale produce oil of four distinct fractions but produces more liquid hydrocarbon product and less gaseous product if the light fractions are removed from the retort chambers before allowing them to be exposed to the temperatures required to retort the heavier fractions. As a matter of interest, certain other types of carbonaecous material, such as Rocky Mountain Oil Shales, release oil at only one temperature range, about 900 degrees F. to 1100 degrees F.
Accordingly, the principal objects of the present invention are to provide a staged retort having multiple retort chambers sealed in such a way to prevent the mixing of liquid and/or gaseous products between them while at the same time permitting the passage of carbonaceous materials from a retort chamber of a lower temperature to a retort chamber of a higher temperature, and to provide means for separately withdrawing the products of pyrolysis formed in each retort chamber so that each of the fractions are kept separate.